hello,

i'm trying to work through the exercises on pages 89-92.
i am not new to crystal, but new to .net.
i really do not understand the difference between an untyped report and a strongly typed report or when which option should be selected.

i completed the exercise on pg 89-90. to complete the untyped report and a strongly typed report exercises on pg 90-92, and i suppose to make another copy of the report and paste the code into it or paste it into the same copy of the report, that was used for the exercise that started on page 89.

it's leaving out items like this that make this book really difficult to follow.

any help would be greatly appreciated.

thanks
indera

I agree with iem. After having read the two sections in the book on untyped reports versus strongly-typed reports I was still left in the dark as to the merits / drawbacks of each. As well, I noticed with some annoyance that the two sections are often identical word-for-word, betraying an obvious cut-and-paste.

What's missing here is an exploration of the three available options: untyped, strongly-typed, and strongly-typed cached, answering the following questions.

1. At a theoretical level, what do these three things mean? There was some attempt to explain the difference between untyped and strongly-typed, but it was much too simple-minded. The exaplanation of what caching means was very clear.

2. Why would I want to / not want to use each of these options? The text simply says that I "probably want to" use strongly-typed reports, and tells me that caching is a good thing. Why, then, did Crystal even bother providing the other options, if I probably shouldn't be bothering with them? Obviously they must serve a purpose. Obviously strongly-typed reports are inappropriate in some circumstances, otherwise untyped reports wouldn't be offered. A discussion of things like ease of programming, runtime flexibility, resource consumption, etc. would have been appropriate.

B P Fraser
Sauder Information Systems

Here, from Microsoft at http://msdn.microsoft.com/library/de...ebprojects.asp, is the explanation that should have been in the book:

This tells me one of the things that I needed to know: why use one option or the other? The answer: use strongly-typed reports if I know at design time that the viewer will be used to view only one report. Use untyped reports if I want a generic viewer that I'm going to connect to a report at run time.

Microsoft's explanation of the "why's" of caching is as weak as the explanation in the book. Now, I'm guessing that caching uses up more memory, and so that's why it's an option and not an automatic feature. That seems logical, but then the point of an instructional book is to come right out and say these things, no?

B P Fraser
Sauder Information Systems

The reason to use Cache is on a report that would be hit frequently. Cache is lightening fast as it loads the complete report to memory rather than having to go to disk, search through the records and write the report. The Drawback as you have mentioned is more memory usage but faster speed. If the report is only used occasionally then it is best not to use cache. This will take a bit longer but does not penalize the memory. Sort of Speed vs memory usage.